NO. 3 UPPER CAMBRIAN TRILOBITE FAUNAS — RASETTI 17 



shale and dolomite. Its exposures are not extensive, and no fossils 

 were observed. The contact with the Copper Ridge dolomite is exposed 

 in a road cut on the S. slope of the ridge. 



Russell Gap. —The lower limestone unit of the Nolichucky is more 

 favorably exposed where a dirt road crosses Shields Ridge at Russell 

 Gap, in the SW. corner of the New Market quadrangle. The overlying 

 shale is poorly exposed in a dip slope in the woods E. of the road. 

 The uppermost limestone is partly exposed only in a ravine E. of the 

 road. The best exposures of the fossiliferous upper portion of the lower 

 limestone unit are located near the crest of the ridge in the woods NE. 

 of the gap. Fossils were collected from the following beds in descend- 

 ing order. 



Collection cnw/14. — Crystalline beds in lower portion (probably 

 lower 10 feet) of upper limestone unit of the Nolichucky. 

 These lower beds are predominantly calcareous, with little 

 shale or dolomite : 

 Aphelaspis tarda r 



*Dunderbergia tennesseensis r 



*Dytremacephalus angulatus c 



*Dytremacephalus sulcifrons rr 



Cheilocephalus hrachyops r 



Collection cnq/14. — Top 1-2 feet of lower limestone unit, under- 

 lying the upper shale unit, about 40-50 feet below the pre- 

 ceding collection. This and the underlying beds are massive, 

 aphanitic limestone with crystalline lenses : 

 Aphelaspis minor c 



Blountia bristolensis c 



Cheilocephalus brevilobus cc 



Glaphyraspis ornata r 



Collection cnp/14. — Massive limestone, about 3 feet below the 

 preceding, hence 4-5 feet below top of lower limestone unit : 

 * Aphelaspis lata c 



Blountia bristolensis cc 



Cheilocephalus brevilobus c 



Glaphyraspis ornata r 



Collection cno/14. — Massive limestone, 11 feet below top: 

 Aphelaspis cf. lata (or buttsi) r 



Blountia bristolensis c 



Cheilocephalus brevilobus c 



Coosella perplexa c 



Glaphyraspis parva r 



Tricrepicephalus, sp. undet. r 



Collection cnn/14. — Massive limestone, 14 feet below top : 

 Blountia, sp. undet. r 



Blountiella, sp. undet. r 



Coosia alethes r 



Coosina, sp. undet. r 



